Your head and heart will never agree. Your head will be the one moving you forward and giving you all the reasons to do so. Your heart will drag from behind, citing all the emotional reasons not to. Your heart will have you make decisions based on the way you feel. That can go against most every time. The way you feel at any one moment can change, so decisions based on that would be an error. Your H has been making decisions based on his feelings, and you can see the results of that.

You can't seem to stop when you know you're approaching the danger zone and about to do something that will set you back? You can stop. You wanted to vent, though. Vent in private. Say to yourself, when you feel like venting at an inappropriate time, "Yes, I feel terrible, angry, and want to vent. I'll vent later." and set aside some time later to explore your feelings. Count to ten. Walk away. Think if this will work for you or against you. When you vent in front of your spouse, it feels good, but it does damage, and convinces your spouse that his decision is right. The OW isn't venting at him, you see. If you slip up and vent to his face, thank him for listening to you and for letting you vent, but don't make it a habit. Though it feels like a release, its effects are temporary and fleeting on you, not him, and sooner or later you'll want to vent again. Set aside a time every morning or evening, perhaps 30 minutes, where you can write a letter about how you feel to him, a letter that you will NEVER have him read or know about. It will help you release your pent up frustrations.